Safety Driving Assist (SDA) is an important part of the current international intelligent transportation system research. It mainly solves the problem of traffic safety and relieves the two problems of traffic congestion and environmental pollution that plague the transportation field. Based on this, many countries in the world are strengthening research in the field of vehicle safety assisted driving technology. Research on safety-assisted driving technology focuses on lane departure warning, front obstacle detection, and driver status monitoring. In the past 20 years, the lane departure warning system has been receiving more and more attention as an integral part of the field of safety-assisted driving research. Many countries have invested a lot of manpower, material resources and financial resources for system research and development.
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Lane departure warning system research background
According to estimates by the Federal Highway Administration, 44% of all fatal traffic accidents in the United States in 2002 were related to lane departures, and lane departures were also seen as the main cause of vehicle rollover accidents. According to the analysis of the AssitWare website, 23% of motorists sleep at least once on the steering wheel within one month; 66% of truck drivers themselves doze off during driving; 28% of truck drivers have within one month The experience of sleeping on the steering wheel. One of the four drivers experienced a casualty caused by lane departure.
According to the definition of the National Highway Traffic Safety Administration (USA), the lane departure warning system refers to a system that assists the driver in avoiding or reducing lane departure accidents by means of an alarm. A lane departure warning system does not attempt to control the vehicle to prevent possible collisions. The National Highway Traffic Safety Administration's “Road Deviation Avoidance Warning Project Using Intelligent Vehicle Road System Countermeasures†divides the vehicle departure warning system into two main functions: “longitudinal†and “horizontal†lane departure warning. The longitudinal lane departure warning system is mainly used to prevent the lane departure collision caused by the vehicle speed being too fast or the direction is out of control. The lateral lane departure warning system is mainly used to prevent the lane caused by the driver's lack of concentration and the driver giving up the steering operation. Deviate from the collision.
The products that have been commercialized by the lane departure warning system are all vision-based systems. According to the camera installation location, the system can be divided into:
Side view system - the camera is mounted on the side of the vehicle, pointing obliquely to the lane;
Front View System - The camera is mounted on the front of the vehicle, diagonally pointing to the front lane.
Both the side view system and the front view system are composed of three basic modules: road and vehicle state perception, lane departure evaluation algorithm and signal display interface. The system first senses the road geometry and the dynamic parameters of the vehicle through the state perception module, and then evaluates the possibility of lane departure by the lane departure evaluation algorithm, and alerts the driver through the signal display interface when necessary.
Foreign lane departure warning system
1.AURORA system
The system was developed in 1997 by the Robotics Institute of Carnegie Mellon University. The system consists of a color camera with a wide-angle lens, a digitizer and a portable SunSparc workstation. The system detects the lane markings next to the vehicle through a color camera mounted on the side of the vehicle with a field of view of approximately 1.5m-1.6m. The video output of the camera is captured by a digitizer and processed on a portable SunSparc workstation. It is 60Hz.
2.AutoVue system
The system was jointly developed by former DaimlerChrysler and Iteris in the United States. The system consists mainly of a camera mounted on the rear of the windshield inside the car, two stereo speakers, a small display device and a control unit.
The working principle of the system is to monitor the position of the vehicle in the current lane in real time, calculate the distance from the vehicle to the lane marking line, and then compare with the set alarm distance to determine whether to make an early warning. When it is detected that a lane departure is about to occur, it will emit a rumbling sound similar to that when the vehicle is driving on the vocal cord to alert the driver to correct the vehicle position. Currently, the AutoVue system has been equipped as an option on a variety of trucks in Europe.
3.Mobileye_AWS system
The system was developed by Mobileye, based in the Netherlands. The system monitors the lane markings with a single camera mounted on the front windshield to measure and monitor the distance between the vehicle and the road boundary. The lane departure warning module of the system detects the position of the vehicle relative to the lane and the lateral movement of the vehicle by detecting the road boundary, predicting the time when the vehicle will traverse the lane marking, and when the time is lower than the set value, the system triggers a visual warning and Sound warnings to allow the driver to respond appropriately to different dangerous conditions and reduce accidents. The system suppresses the generation of warnings in the case of conscious lane departures, braking and no road markings.
4.DSS system (DriverSupportSystem)
The system was proposed by Japan's Mitsubishi Motors Corporation in 1998 and was applied to model cars in the fall of 1999. The system consists of a small CCD camera mounted in the rearview mirror of the car, sensors that detect vehicle behavior and driver behavior, and visual and audible warning devices. The system uses information such as lane identification lines in front of the vehicle obtained by the CCD camera, vehicle status data obtained by other sensors, and driver's operational behavior to determine whether the vehicle has begun to deviate from its lane. If necessary, the system will use visual warnings, audible warnings, and vibrating steering wheels to alert the driver to drive the vehicle carefully.
Domestic lane departure warning system
1.JLUVA-1 system
The system was developed by the Jilin University Intelligent Vehicles Task Force. The system is based on monocular vision front view system, which is mainly composed of vehicle power supply, embedded microcomputer, display device, black and white CCD camera, data line, speaker and image acquisition card.
The system uses the CCD camera installed at the position of the rearview mirror of the car to collect the road image in front of the car, and obtains the position parameter of the car in the current lane through image processing. When it is detected that the car is too close to the white line of its own lane, it may be biased into the adjacent lane. And when the driver does not turn on the turn signal, the system will issue a warning message to alert the driver to correct this unintentional lane departure, thus minimizing the occurrence of lane departure accidents.
2. Embedded lane departure warning system based on DSP technology
Developed by Southeast University, the system is a front-view system based on monocular vision. It consists of modules such as analog-to-digital conversion and decoding circuit blocks, buffer circuit modules, media processor DSP circuit blocks, encoding and digital-to-analog conversion circuit modules. The system collects the analog video signal of the tracked lane line through the vehicle camera, decodes and generates the digital signal stream buffer and sends it to the video interface of the high-speed media processor DSP, and then the video processing module performs the lane feature value on the digital video signal. Extracting, finally, the processed video signal is sent to the encoding and the digital-to-analog conversion circuit outputs the display.
The study of lane departure warning systems is mainly focused on the vision-based lane departure warning system. However, from the current technical level, the most important factor affecting the reliability of the vision-based lane departure warning system is the weather conditions applied by the system and the influence of illumination changes, which is a major problem currently faced by all vision systems. At present, the study of various lane departure evaluation algorithms with strong robustness, adaptability to various weather conditions, overcoming illumination changes and shadow conditions is the development trend of all vision-based lane departure warning systems.
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